In the production of hems in garments, such as a hem in a T-shirt sleeve, it is desirable to provide a perfect blind stitch. A perfect blind stitch is indicated if one stitches black cloth with white thread from the inside, and after hemming by normal viewing one can't see the white thread from the outside of the garment, only from the inside. Heretofore it has not been possible to automatically fold over the edge of a garment during hemming so as to positively hold the garment in place so that when acted upon by an automatic sewing machine a blind stitch occurs. While heretofore there have been provided static folders in association with automatic sewing machines--even including one "down type" folder in which the cloth drapes into a relatively natural position during operation thereon rather than being held in an artificial position--it has never been possible to control precisely enough the distance between the needle of the automatic sewing machine and the component of the static folder holding the garment in folded position, so as to form a perfect blind stitch.
One of the major difficulties with prior art folders that have resulted in the deficiency described above has been the fact that the folders have always been mounted on the conveying part of the machinery, not on the sewing machine head itself. According to the present invention a static folder of a "down type", with a particularly desirable configuration, is mounted directly on the sewing machine head, preferably in place of the conventional cloth plate on the sewing machine. The folder is preferably mounted by a pivot post adjacent one end thereof, and a releasable latch adjacent the opposite end thereof.
According to one aspect of the present invention, a down type static folder for folding the edge of a garment during hemming--such as a T-shirt to provide a hem of about one-half to one inch--is provided in combination with an automatic sewing machine head having a needle. The folder comprises: Static plate means for effecting fold over of the edge of a garment brought into operative association therewith. Tongue means operatively connected to the plate means for holding the folded over edge of a garment in a predetermined relationship with the needle of the automatic sewing machine during hemming of the garment edge by the sewing machine. And, means for mounting the static plate means and the tongue means in a specific predetermined relationship directly to the sewing machine head so that the tongue is in close proximity to the needle. Preferably the mounting means mounts the tongue within about 0.0012-0.0015 inches from the needle and the tongue extends outwardly and upwardly from the plate means.
According to another aspect of the present invention a method of forming a perfect blind, permanently set stitch in a garment (e.g. a T-shirt sleeve blank) is provided, utilizing an automatic sewing machine having a needle and a static folder. The method comprises the following steps: (a) Automatically conveying a garment blank, having a free edge, in a first direction into operative association with the static folder. (b) Automatically effecting folding over of the garment free edge to forming a hem by the static folder acting on the garment conveyed into operative association therewith. And, (c) automatically stitching the folded over garment hem to permanently set it, and trimming excess material from the hem, while holding the hem in close tolerance to the needle of the automatic sewing machine, to provide a perfect blind stitch.
According to yet another aspect of the present invention, a static folder for use with an automatic sewing machine is provided. The static folder comprises: A supporting channel. A first plate mounted to the supporting channel, the first plate having tongue means operatively connected thereto for holding the folded edge of a garment in a predetermined position. A second plate, including a pivot pin extending downwardly therefrom. Means for mounting the first plate to the second plate and to the channel, so that the pivot pin extends downwardly from the second plate away from the first plate, in the dimension toward the channel. And, means for providing adjustment of the tongue means with respect to the second plate.
It is the primary object of the present invention to provide a method and apparatus for effecting a perfect blind stitch in a garment blank, such as in a T-shirt sleeve. This and other objects of the invention will become clear from an inspection of the detailed description of the invention and from the appended claims.